1. Technical Field of the Invention
The present invention generally relates to the telecommunications field and, in particular, to a mobile telecommunications network and method for implementing and identifying hierarchical overlapping radio coverage areas including at least one location area and at least one routing area.
2. Description of Related Art
A mobile telecommunications network may have many types of architectures according to a variety of standards such as the Personal Digital Cellular (PDC) standard used in Japan, or the Global System for Mobile Communications (GSM) and General Packet Radio Service (GPRS) Standards used in Europe.
The mobile telecommunications network having the architecture in accordance with the PDC standard generally includes a multitude of contiguous location areas, where each location area effectively divides an arbitrary geographic area into a plurality of cells. The PDC standard also supports a feature where the location areas can be overlapped to avoid a "ping-pong" effect and reduce the concentration of location updates within cells located along a border between contiguous location areas.
The "ping-pong" effect occurs when the mobile terminal moves back-and-forth across the border between contiguous location areas and, as a result of such movement, initiates multiple location updates with the mobile telecommunications network. The initiation of multiple location updates or location registrations is problematic due to the utilization of valuable resources by the mobile telecommunications network. Therefore, a definite advantage of the PDC standard is the support and availability of overlapping location areas.
Referring to the GSM/GPRS standards, the architecture of the mobile telecommunications network according to such standards permits the use of hierarchical location area structures in which location areas cover large geographical areas and routing areas (same as location area but used on a lower hierarchical level) cover smaller geographical areas. The location areas of the GSM standard represent a higher hierarchical level used for supporting circuit switched calls. And, the routing areas of the GPRS standard represent a lower hierarchical level used for supporting packet data switched calls. Of course, a definite advantage associated with the GSM/GPRS standards is the availability of hierarchical location area structures.
Unfortunately, the current mobile telecommunications networks do not support the combined use of the overlapping feature of the PDC standard and the hierarchical location area structures feature of the GSM/GPRS standards. It is believed that the failure in supporting the combined use of such features may be due to the difficulty associated with identifying the multiple location areas and multiple routing areas that can be accommodated by each one of the cells.
Also problematic, is the coupling of the overlapping feature of the PDC standard with temporary mobile subscriber identity (TMSI) and temporary logical link identity (TLLI) features of the GSM/GPRS standards. Each of the TMSI and TLLI features currently operate in a situation where the mobile user (please note that mobile terminal and mobile user are used interchangeably herein) is assigned a temporary identifier that is used instead of a real subscriber identity when communicating across a radio interface. Unfortunately, the problem occurs when the overlapping feature is combined with the TMSI and TLLI features in that the temporary identifiers may no longer be unique within cells accommodating multiple location areas and/or multiple routing areas.
Accordingly, there is a need for a method and mobile telecommunications network that combines the features of the hierarchical location area structures associated with the GSM/GPRS standards with the overlapping feature associated with the PDC standard. There is also a need for a method and mobile telecommunications network for identifying the newly formed hierarchical overlapping radio coverage areas including at least one routing area and at least one location area. These and other needs are satisfied by the mobile telecommunications network and method of the present invention.